This invention relates generally to digital data transmission, and more particularly, the present invention relates to a method and system for producing a synchronous signal from a train of digital data blocks transmitted with no synchronous signal.
Among various methods of detecting errors in digital data transmission, a method of cyclic redundancy check (CRC) is considered to be effective. For instance, when a PCM signal obtained by converting an analog signal, such as an audio signal into a PCM digital signal, is transmitted to be recorded, reproduced or the like, redundant bits are usually added to the data bits so that CRC can be performed to detect errors. In such a method of data transmission, a synchronous bit word is interposed between two consecutive data blocks each including the data carrying necessary information and the above-mentioned redundant bits, so that the synchronous bit word will be detected to distinguish one data block from another in a receiving end. In the conventional method, therefore, the synchronous signal bit word is essential because each data block cannot be distinguished from another without such a synchronous signal bit word. This has been an obstacle in increasing data transmission rate.